Users on the Internet require speed and reliability when requesting content from web servers. The web servers may have a delay in providing content or may intermittently fail to provide content because of technical problems. Web proxies can cache content sent to clients with the goal of enabling subsequent requests to be handled more quickly or reliably. Web proxies can cache a copy of content for a requested Uniform Resource Identifier (LTRI), Uniform Resource Locator (URL), Uniform Resource Name (URN), or other link that identifies the content, and can provide the cached copy in subsequent requests for the same link.
To request content, users typically employ a variety of types of client devices with different characteristics and capabilities, including a client computer, a mobile device, or the like. These client devices may request the same content differently and a number of different conditions (e.g. network state) may affect content delivery to these clients. Still other factors may affect content delivery, such as differences in client connection speed, a client's browser capability or the like. Additionally, some client devices may be unable to display or otherwise receive content in a particular format. Moreover, some users of client devices may be restricted from accessing particular content based on security policies, or the like.